Encoders and resolvers that detect the rotational position of motor shafts, for example, are widely known for conventional rotational position sensors.
In addition, for rotational position sensors used for steering shafts provided in vehicles, for example, structures where a coiled groove is formed in the worm gear that rotates with the steering shaft, and the swinging arm of a rotational position meter is hooked into this coiled groove are known. With this rotational position sensor, the swing arm is swung and rotated by the worm wheel, and the resistance value for the position meter changes. Furthermore, the rotational position of the steering shaft has been detected based on the position meter output voltage. Such conventional rotational position sensor is described in, for example, Japanese Patent Application Publication No. 2005-114676, at [0023]-[0027] and FIG. 2.